Merge branch 'stream_refactor' into develop

.gitignore

synapse/api/notifier.py

synapse/api/streams/event.py

synapse/handlers/events.py

synapse/handlers/presence.py

synapse/handlers/room.py

synapse/notifier.py

synapse/rest/events.py

synapse/rest/initial_sync.py

synapse/rest/room.py

synapse/server.py

synapse/storage/stream.py

synapse/streams/__init__.py

synapse/streams/config.py

synapse/streams/events.py

synapse/types.py